1. Field of the Invention
The present invention relates to an optical coherence tomographic imaging device and an imaging method of an optical coherence tomographic image, and particularly relates to an optical coherence tomographic imaging device and an imaging method of an optical coherence tomographic image used in ophthalmic diagnosis, treatment, and the like.
2. Description of the Related Art
Various ophthalmologic apparatuses using optical devices are used at present.
For example, as for optical devices for observing eyes, various kinds of devices such as an anterior ocular segment photographing device, a fundus camera, and a confocal scanning laser ophthalmoscope (Scanning Laser Ophthalmoscope: SLO) are used.
Among them, an optical coherence tomographic imaging device by optical coherence tomography (OCT) using multiwavelength light wave coherence can obtain a tomographic image of a specimen at high resolution. The device is on the way to becoming indispensable in outpatient clinics specialized in retinas as an ophthalmologic device.
Hereinafter, the device will be described as an OCT device.
According to the above described OCT device, a sample is irradiated with a low coherent light, and the reflected light from the sample can be measured at high sensitivity by using a coherent system.
Further, the OCT device can obtain a tomographic image at high resolution by scanning the low coherent light over the sample.
Therefore, the OCT device can image the tomographic image of the retina in the eyeground of an examined eye. Thus, the OCT devices are widely used in the ophthalmologic diagnosis of retinas.
Meanwhile, in recent years, there has been a growing demand for obtaining tomographic images at high resolution in such optical coherence tomographic imaging devices.
Therefore, various devices have been conventionally developed. Japanese Patent Application Laid-Open No. 2002-174769 discusses an optical device for observing the inside of a biological specimen by properly using an OCT and OCM (Optical Coherence Microscopy).
In this device, the OCT is used for checking a large structure in a biological specimen, and the OCT can be switched to the OCM when observing a notable region in the structure with higher resolution.
At this time, since the OCT and OCM differ greatly in depth of focus (DOF), a beam diameter converting optical system is used so that the beam diameters corresponding to the OCT having a small numerical aperture and the OCM having a large numerical aperture can be set, and observation at a high Signal-to-Noise (S/N) ratio can be made.